CHLORPYRIFOS JMPR 1975
Explanation
Chlorpyrifos was considered by the Joint Meeting in 1972 and an
ADI was established (FAO/WHO, 1973). Based on information reported at
that Meeting and at the 1974 Meeting (FAO/WHO, 1975), a number of
further recommendations for tolerances were specified on both animal
and vegetable products.
During the CCPR Meeting 1975 some delegations expressed opinions
on individual tolerances reflecting different views on good
agricultural practices, and specific levels established for poultry
fat and for milk were questioned. As no information has been received
concerning residues in vegetable products, the Meeting has only
considered the questions raised on poultry fats and milk products.
RESIDUES IN FOOD AND THEIR EVALUATION
In poultry fat
A chicken feeding study by Dishburger et al. (1972) which has
been brought to the attention of the Meeting elucidates the question
of chlorpyrifos residues in poultry fat further. In this study laying
hens were fed chlorpyrifos at rates of 0.3, 1.0, 3.0 and 10 mg/kg for
30 days. Samples of muscle (with fat and skin), liver, kidney and
peritoneal fat were analysed, as were eggs from hens fed 10 mg/kg over
a period of 45 days. Chlorpyrifos and 3,5,6-trichloro-2-pyridinol were
determined (see Table 1) and analysis showed that the level of the
parent compound in chicken fat is not likely to exceed 0.1 mg/kg under
practical circumstances following good agricultural practices.
Residues of chlorpyrifos in eggs were not detectable.
Another source of chlorpyrifos residues in poultry fat was
reported earlier (FAO/WHO, 1973), namely the more specific practice of
controlling chiggers, Neschongastia americana in turkeys through
soil-treatments in pens. As a result of this application some of the
compound is take up by the turkeys and maximum residues of 0.157 and
0.066 mg/kg in skin and fat respectively were found one week after the
treatment (Claborn et al., 1970) declining to less than 0.001 mg/kg
after six weeks.
While the earlier recommendation of 0.2 mg/kg for chlorpyrifos in
poultry fat could therefore be lowered to 0.1 mg/kg as far as chicken
fat is concerned, this would not be justified in the case of turkey
fat and skin.
TABLE 1. Average residues of chlorpyrifos and 3,5,6-trichloro-2-pyridinol in tissues and eggs of chickens fed chlorpyrifos
Average residues found, mg/kg
Chlorpyrifos 3,5,6-trichloro-2-pyridinol
Chlorpyrifos
level in
feed mg/kg Muscle Liver Kidney Fat Eggsa Muscle Liver Kidney Fat Eggsa
0 - - - - - - - - - -
0.3 - - - - - - ND ND - -
1.0 - - - ND - - ND ND-0.11 - -
3.0 - - - ND-0.02 - - ND-0.06 ND-0.24 - -
10.0 ND ND ND 0.02-0.06 ND ND ND-0.25 ND-0.84 ND ND-&lt0.05
10.0b - - - ND - - ND ND - -
a Eggs collected from chickens on treated feed 7-45 days - no withdrawal period.
b 7-day withdrawal from medicated feed.
In milk and milk products
Studies of the transfer of chlorpyrifos into milk after feeding
cows at the 5 mg/Kg level and reports on milk residues resulting from
single dip applications were evaluated by the JMPR 1972 and no new
information has become available.
In response to the question raised by the CCPR, the Meeting
reconsidered the data already available and recognized that the
previous recommendation reflects only the reported feeding studies,
whereas residues arising from direct dip applications (Table 5 of
FAO/WHO 1973) may not be sufficiently covered by the established
maximum residue limit of 0.01 mg/kg. Taking into account the
increasing use and potential interest in such applications, a maximum
residue of 0.1 mg/kg is required. In proposing this limit the Meeting
recognized that the milk from treated cows will, in normal practice,
be blended with milk from untreated cows and that it would be unlikely
for more than a proportion of commercial milk to come from recently
treated cows, even in areas where treatments have to be repeated
frequently (FAO/WHO, 1972).
APPRAISAL
In response to questions raised by the Codex Committee on
Pesticide Residues, the Meeting has reconsidered the earlier
established tolerances for chlorpyrifos in poultry fat and milk. Based
on new information from chicken feeding studies, the earlier
recommended tolerance of 0.2 mg/kg in poultry fat could be lowered to
0.1 mg/kg as far as chicken fat is concerned. However, the earlier
recommendation should be maintained to account for the higher residues
in fat and skin of turkeys which may arise from soil treatments in
turkeys' pens in the control of chiggers.
Having re-evaluated the earlier recommendation for a tolerance of
0.01 mg/kg for chlorpyrifos in milk (fat basis), the Meeting agreed
that this level was not adequate to cover residues which may result
from dip applications to dairy cattle. An increase of the earlier
proposal to 0.1 mg/kg is appropriate.
RECOMMENDATIONS
Earlier established tolerances (FAO/WHO, 1973, 1975) should be
amended as follows, by deleting tolerances for fat of poultry and for
milk and inserting:
Commodity Maximum residue limit, mg/kg
Fat and skin of turkey 0.2
Fat of chicken 0.1
Milk and milk products (fat basis) 0.1
Eggs (whole) 0.01*
* At or about the limit of determination.
REFERENCES
Claborn, H. V., Kunz, S. E. and Mann, H. D. (1970) Residues of Dursban
in the body tissues of turkeys confined in pens containing treated
soils. J. Econ. Entomol., 63:422-424.
Dishburger, H. J., McKellar, R. L. and Wetters, J. H. (1972) Residues
of chlorpyrifos and 3,5,6-trichloro-2-pyridinol in tissues and eggs
from chickens fed chlorpyrifos. Report from Dow Chemical USA, Midland,
Michigan, 31 May.